The present invention relates generally to a method and apparatus for radio spectrum analysis. More particularly, the present invention relates to a method and apparatus for remote radio spectrum analysis.
Wireless communications in general, and cellular telephone systems in particular, are becoming increasingly popular. As a result, cellular telephone systems are becoming increasingly complex. These systems are generally made up of cell sites, each of which serves a coverage area, or cell. The cell site is the location within a cell which contains the required hardware (e.g. antenna(s) and radio base station) to communicate with mobile telephones. A mobile telephone operating within a particular cell in the system communicates with the mobile telephone system through the cell site covering that cell. The various cell sites are connected to a mobile telephone switching office which connects the cellular telephone network to the land line telephone network.
Cellular telephone system providers are generally licensed to operate a cellular telephone network in a particular geographic area using a specified frequency spectrum for radio communication between mobile telephones and the base stations. For example, a typical cellular system provider may have a license to operate in a 12.5 MHz spectrum. This spectrum may be divided into 416 channels, each 30 KHz wide. Each of these 416 channels is capable of handling the communication between one mobile telephone and a radio base station. For further information on this air interface, see, EIA/TIA Standard 553, xe2x80x9cMobile Station-Land Station Compatibility Specificationxe2x80x9d, September 1989, Electronic Industries Association, Washington, D.C.; EIA/TIA Interim Standard IS-54-B xe2x80x9cCellular System Dual-Mode Mobile Station Basestation Compatibility Standardxe2x80x9d, April, 1992, Electronic Industries Association, Washington, D.C.; and EIA Interim Standard IS-136 xe2x80x9cCellular System Dual-Mode Mobile Station-Basestation: Digital Control Channel Compatibility Standardxe2x80x9d, April, 1995, Electronic Industries Association, Washington, D.C.
A fixed channel cellular system is a cellular system in which each cell is assigned a fixed group of channels for communication. For example, if each cell were assigned one group of 16 channels, there could be a maximum of 26 (16xc3x9726=416) cells carrying the permissible 416 calls in the serving area if there was no reuse of channels. However, if cells are sufficiently spaced apart, in terms of geographic ground distance, channels can be reused in multiple cells without overlap. Designing a fixed cell system which reuses channels is a complex task. In addition, once a system is in place, it is often necessary to add cells to the system as communication traffic increases. The addition of a cell is also a complex task, and it requires an analysis of the radio spectrum of the area in which the cell is to be added.
To more efficiently use the limited frequency spectrum, schemes other than fixed channel systems are also being studied. One such scheme is called adaptive channel allocation. In an adaptive channel allocation system, the cells are not assigned a fixed group of channels. Instead, the cellular system is self organizing in that each cell dynamically determines which channels it will use for communication. Thus, the system adapts itself based upon the communication traffic. The development and testing of these adaptive channel allocation systems require a detailed analysis of the spectrum profile in the area under consideration.
As seen from the above discussion, spectrum analysis is required during the design and maintenance of cellular telephone networks. Presently, when an engineer needs spectrum analysis information, a technician is sent to the location in question with spectrum measurement equipment. The technician must program the device to take the appropriate measurements. For example, the engineer may only be interested in measuring a certain portion of the spectrum. Once correctly programmed, the device is capable of measuring the spectrum, or portion thereof, and storing spectrum data on storage media, such as a magnetic disk. The disk can then be sent to the engineer for analysis. One disadvantage of this type of device is that it needs to be reprogrammed by a technician on site when it is moved from one location to another and when different measurements are required. Another disadvantage occurs because an engineer is often interested in measuring the spectrum at a location that is remote from the engineers location. In such a situation, the data must be stored on a storage device and physically sent to the engineer.
Thus, there is a need for a remote spectrum measuring device which can be remotely programmed and which can automatically transmit measurement data over a communication network to an end user at a remote location.
The present invention provides a method and apparatus for remote spectrum analysis. During a measurement phase, a channel measurement device measures signal information in a geographic area. Data representing the measured signal information is stored in a storage device. During a data transfer phase, the stored data is transmitted to a remote processor via a communications network. Thus, a user at a remote location can analyze the data measured by the channel measurement device. The communications network used for the data transfer may be, for example, a land line telephone network or a cellular telephone network.
Various functions of the channel measurement device may be controlled by a user at a remote location. The functions of the channel measurement device are controlled in part by user programmable configuration parameters. These parameters may be set by a user at a remote location using a remote processor. The remote processor sends the configuration parameter values to the channel measurement device via the communications network.